Spring trip multi-phase overload relay having a u-shaped bimetal with a pivot pin at its web portion



Nov. 29, 1966 J. B. CATALDO ET AL 3,23

SPRING TRIP MULTI-PHASE OVERLOAD RELAY HAVING A U-SHAPED I BIMETAL WITHA PIVOT PIN AT ITS WEB PORTION Filed June 1. 1965 5 Sheets-Sheet 1 Nov.29, 1966 J. B. CATALDO ET AL S PRING TRIP MULTI-PHASE OVERLOAD RELAYHAVING A U-SHAPED BIMETAL WITH A PIVOT PIN AT ITS WEB PORTION 5Sheets-Sheet 2 Filed June 1, 1965 Nov. 29, 1966 J. B. CATALDO ET3,283,954

SPRING TRIP MULTI-PHASE OVERLQAD RELAY HAVING A U-SHAPED BIMETAL WITH APIVOT PIN AT ITS WEB PORTION Filed June 1, 1965 5 Sheets-Sheet 5 Nov.29, 1966 J. B. CATALDO ET 3,

SPRING TRIP MULTI-PHASE OVERLOAD RELAY HAVING A U-SHAPED BIMETAL WITH APIVOT PIN AT ITS WEB PORTIQN Filed June 1, 1965 5 Sheets-Sheet 4 Nov.29, 1966 J. B. CATALDO ET L 3,238,964

SPRING TRIP MULTI-PHASE OVERLOAD RELAY HAVING A U-SHAPED BIMETAL WITH APIVOT PIN AT ITS WEB PORTION Filed June 1, 1965 5 Sheets-Sheet 5 UnitedStates Patent f SPRING TRIP MULTl-PHASE OVERLOAD RELAY HAVING A U-SHAPEDBlMETAL WITH A PIVOT PIN AT ITS WEB PORTIUN John B. Cataldo, BloomfieldHills, Elwood T. Platz, Grosse Pointe, Frank W. Kussy, Birmingham, andBernard Di Marco, Lincoln Park, Mich, assignors to I-T-E Circuit BreakerCompany, Philadelphia, Pa., a corporation of Pennsylvania Filed .lune 1,1965, Ser. No. 460,204 15 Claims. (Cl. 200-116) In general the instantinvention relates generally to overload relays of the type combined withelectro-magnetic contactors to form motor controllers and in particularrelates to a multi-phase overload relay of this type having spring tripmeans for separating the cooperating contacts of the coil energizingcircuit upon the occurrence of overload conditions in any of the phases.

Copending application Serial No. 225,044 filed September 20, 1962,entitled Overload Relay for Motor Starters with Robert W. Thomas et al.as inventors and assigned to the assignee of the instant invention,discloses a single phase overload relay. For multi phase operation twoor more such single phase relays are combined with an electro-magneticcontactor. It often happens that for multi phase applications, ratherthan utilizing a plurality of single phase overload relays it has beenfound advantageous to utilize a single so-called block-type relay.

In essence, a block type overload relay is a unit providing individualbimetal elements for detecting fault conditions in two or more of thephases to be protected. The block type overload relay is so constructedthat upon the occurrence of an overload in any of the phases the bimetalof that particular phase will operate to open a pair of cooperatingcontacts in the energizing circuit of the contactor coil therebydeene-rgizing the contactor.

Prior art block type overload relay constructions have either beenunduly complicated and/or the bimetals of each phase were undulyinfluenced by the heaters of the other phases. To overcome thesedisadvantages of the prior art the instant invention provides arelatively simple construction in which the influence between theheaters of different phases is reduced by placing the bimetal for eachphase in a separate pocket and separating the pockets from one anotherby air spaces. The undesirable effects of heating in adjacent spaces isfurther reduced by mounting the bimetals in a manner such that they arein minimum surface engagement with the housing so as to avoid heatconduction. 'Bimetal heating influence between phases is still furtherreduced by having each bimetal actuate its own over-center spring withthe latter operating upon a common trip bar.

Accordingly, a primary object of the instant invention is to provide anovel construction for a so-called block type multi-phase overloadrelay.

Another object is to provide an overload relay of this type in which theaffects of heating in one phase are reduced in the other phase.

Still another object is to provide an overload relay of this type havinga common adjusting bar and a common trip bar.

A further object is to provide a novel overload relay of this type inwhich each pole is in line with the corresponding load terminal of thecontactor so that a mechanical connect-ion from the overload relay tothe contactor straps automatically becomes an electrical connection.

A still further object is to provide a novel overload relay of this typewhich requires no more than two parts to form the housing for all phasestogether as well as the switching and resetting elements.

These as well as other objects of this invention shall 3,288,964Patented Nov. 29, 1966 become readily apparent after read-ing thefollowing description of the accompanying drawings in which:

FIGURE 1 is a perspective of a block type overload relay constructed inaccordance with the teachings of the instant invention.

FIGURE 2 is a front elevation of the overload relay of FIGURE 1.

FIGURE 3 is an end view of the overload relay of FIGURE 1.

FIGURES 4, '4, 6, and 7 are cross-sections taken through the respectivelines 4-4, 55, 66 and 77 of FIGURE 2 looking in the directions of therespective arrows. In this group of figures only the structural elementsbeing described in detail are shown, the other elements having beenremoved to avoid confusion.

FIGURE 8 is a perspective of a tripping spring and its mounting membertogether with the element engageable with this spring for trippingthereof.

FIGURE 9 is a perspective of the common adjusting bar.

FIGURE 10 is a perspective of the common trip bar.

FIGURE 11 is a perspective show-ing the front of the housing cover andthe elements mounted thereto.

Now referring to the figures. Block type overload relay 15 is a threephase unit typically of such a size as to be used in conjunction withcontactor 16, partially shown in FIGURES 4 and 7, to form a motorstarter. For a detailed description of contactor 16 reference is made tothe Cataldo et al. copending application Serial No. 189,915 filed April24, 1962, entitled Electrical Device and assigned to the assignee of theinstant invention.

Overload relay 15 is provided with a housing consisting of hollow base17 and plate-like rear cover 18 mated along line 19 and secured togetherby means of screws (not shown). Essentially base 17 is divided into aseries of parallel compartments. That is, there are three maincompartments, one for each of the current carrying phases of overloadrelay 15 The main compartments are separated by two narrowercompartments which house the automatic reset lock element 21 and themanual reset plunger 22 respectively. It is noted that extensiveportions below these narrow compartments are void of mechanism so as toprovide dead air spaces between the main compartments thereby reducingthe heat transfer between these main compartments. The right side ofbase 17 with respect to FIGURE 2 is formed as a narrow short compartment23 which houses the main and signalling contacts 51, 54, 56.

Since the current carrying elements of all three phases are identical,only those current carrying elements associated with phase A (the leftof FIGURE 2) will be described. This current path consists of lineterminal strap 25, U-shaped bimetal heater 26, load terminal strap 27and wire grip 27a. Line terminal strap 25 is a generally L-shaped memberhaving a vertical leg riveted or otherwise suitably secured to the frontside of cover 18 and positioned between the upwardly protruding barriers28a, 2%. Screw 29 removably secures one leg of bimetal heater 26 to thehorizontal leg of line terminal 25 while screw 38 secures the other legof bimetal heater 26 to a generally horizontal portion of load terminal27. Rivets 31 (FIGURE 2) secure a vertical portion of load terminal 27to the front surface of base 17.

Heater 26 is positioned between the arms of U-shaped bimetal 33 which ispivotally mounted to base 17 by means of pin 34. The ends of pin 34extend beyond the sides of bimetal 33 and are received in pivot definingapertures in the arms of U-shaped retaining member 35. The latter isreceived by suitable formations of base 17 and retained in operativeposition by forward protrusion 36 of cover 18 which engages the webportion of member 35 (FIGURE 4). The free end of bimetal calibrating leg33a abuts the rear end of calibration screw 37 with the latter beingthreadably mounted to the downward radial extension 38a of commonadjusting bar 49. The head of screw 37a is aligned with front aperture39a of base 17 so as to be accessible for adjustment of bimetal 33.

The free end of bimetal tripping leg 33b is positioned to engage theforward edge of member 41. More particularly, when heater 26 issubjected to overload current the heat generated thereby causes the freeends of the bimetal legs to diverge. Movement of calibrating leg 33a isrestricted by calibration screw 37 so that movement is limited totripping leg 33b with the latter moving to the left with respect toFIGURE 4 thereby moving member 41 in a generally horizontal path definedby slots in base 17. When member 41 engages center leg 42a of bistablespring trip member 43 the latter is movable from the solid to dottedline position of FIGURE 4. Leg 42a is positioned between legs 42b and42c. The latter two legs are riveted near the free end thereof to theforwardly offset leg of mounting member 45 with member 45 being fixedlysecured to the forward surface of cover 18.

In a manner well known to the art, as legs 42b and 420 are secured tomember 45 appropriate stresses are set up in member 43 to permit thelatter to be operated between two bistable positions. That is, when leg42a is moved to the left, in a counter-clockwise direction with respectto FIGURE 4, as leg 42a moves just slightly to the left of legs 42b and420 the bistable characteristics of spring member 43 causes leg 42a andthe upward extension 43a thereof to move with a snap action in theclockwise direction with respect to FIGURE 4.

As this movement takes place extension 43a engages radial projection 47aof common trip bar 50 thereby pivoting bar 50 in a clockwise directionwith respect to FIGURE 4 and a counter-clockwise direction with respectto FIGURE 7. This motion of common trip bar 50 is effective to move itsradial switch arm 51 from its solid line position of FIGURE 7 to thedotted line position thereof. The free end of switch arm 51 mountscontact member 99 which is connected at its upper end to currentcarrying spring member 52 extending downwardly from U-shaped terminalmember 53. In the solid line position switch arm 51, contact 98 carriedby member 99 is in engagement with main contact 54 secured to the lowerleg of Z-shaped terminal member 55 while in the dotted line position forswitch arm 51, contact 97 carried by member 99 is in engagement withsignalling contact 56 mounted to the lower end of offset terminal strap57. As illustrated in FIGURE 7, with switch arm 51 in its solid lineposition the contactor coil energizing circuit is completed through theelectrical connection provided by L-shaped conducting strap 58connecting terminal strap 55 to coil terminal 59 of contactor 16. Withswitch arm 51 in the dotted line position of FIGURE 7 it may be utilizedto control a signalling circuit which indicates that tripping has takenplace.

In a manner well known to the art, common trip bar 50 extends throughall phases A-C of overload relay 15 and is positioned by means ofappropriate recesses in the partitions defining the chambers in base 17in cooperation with forward projections 61 of cover 18. Similarly,adjusting bar 40 extends through the three main compartments and ispositioned by cut-outs in the walls of base 17 defining thesecompartments. Insulating cover strip 62, retained in position by theoverlapping vertical portions of terminal member 27, prevents forwardmovement of common adjusting bar 40. Wire spring 63 (FIGURE biases bar40 in a counter-clockwise direction with respect to FIGURES 4 and 5 sothat the long radial extension 3811 of bar 40 remains firmly seatedagainst the rear end of adjusting screw 65.

In order to calibrate overload relay the head of adjusting screw 65 ispositioned with the protrusion thereof pointing to 100 as seen in FIGURE2. Thereafter, the calibration screws 37 for each of the phases A, B andC are individually adjusted so that the respective bimetals 33 arepositioned to bring about tripping under predetermined overloadconditions. Apertures 39 are then blocked by sealing compound so thatcalibrating screws 37 may not be tampered with in the field. Fieldadjustment for overload relay 15 takes place by means of adjusting screw65 which is limited to a rotation of slightly less than one revolutionbecause of the engagement of head protrusion 65a with base surfaces 66a,6612.

After tripping has taken place reset slide 22 is utilized for manuallyoperating one or more of the spring trip members 43 to their solid linepositions illustrated in FIGURE 4. That is, the lower edge of resetslide 22 is provided with inclined surface 22a which, upon downwardmovement of reset slide 22, engages common trip bar radial projection 67causing the latter to move to the left with respect to FIGURE 5 and inso doing rotating common trip bar 50 in a counter-clockwise direction.This brings trip bar projection 4711 into engagement with spring memberprojection 43a causing the latter to rotate in a counter-clockwisedirection with respect to FIGURE 4 thereby operating leg 42 to the solidline position illustrated in FIGURE 4. Spring 68, retained by screw 69,urges reset slide 22 to its upper position illustrated in FIGURE 5.

Automatic reset member lock 21, as best seen in FIG- URES 2 and 6, isselectively positioned in one of two setting member 22.

positions depending on which bulge in slot 21a screw 70 extends through.With lock 21 in its lower position as illustrated automatic reset member72 is disposed so that overload relay 15 will automatically reset aftertripping. That is, lock 21 acts to hold member 72 against the force ofits biasing spring 73 to the position shown in FIGURE 6. This positionsmember 72 in the path of common tripping bar projection 74 to limitpivotal movement of tripping bar 50 to a position such that spring tripmember 43 does not move over center in the tripping direction.Accordingly, after a tripping operation has taken place, as bimetal 33cools trip member 43 will automatically move to its solid line positionillustrated in FIG- URE 4 thereby permitting contact arm 51 to engagemain contact 54 without the necessity of utilizing manual re- Obviously,with reset member lock 21 raised, spring 73 moves member 72 to the rightwith respect to FIGURE 6 to a position clear of projection 74 so thattrip members 43 are free to snap over center to the trip position.

It is noted that the line terminals 25 of overload relay 15 arepositioned substantially in line with the load terminals of contactor16. Thus, terminals 25 may readily be mechanically and electricallyconnected to the load terminals of contactor 16 by utilizing threeoffset straps 99 (FIGURE 4). Further, by simply utilizing L-shaped strap58 the terminal member 55, carrying main contact 54, may readily beconnected to terminal 59 extending from one of the terminals of thecontactor coil.

Thus, this invention provides an improved block type overload relay ofrelatively simple construction. This relay is provided with a generallyU-shaped bimetal pivotally mounted at the web of the U with one of theU- arms being utilized for calibrating purposes and the other U-armbeing utilized to actuate a spring trip means. Individual calibratingmeans are provided for each phase while a common adjusting bar isutilized for field adjustments. Further, a common tripping bar isutilized so that only a single set of contacts connected in thecontactor coil circuit are necessary.

Although there has been described a preferred embodiment of this novelinvention, many variations and modifications will now be apparent tothose skilled in the art. Therefore, this invention is to be limited,not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

1. An overload protective device including an electric heater, agenerally U-shaped bimetal element having spaced arms connected by a Webportion, said bimetal element mounted in spaced relation with respect tosaid heater and in close proximity thereto so that heat generated bycurrent fiow through said heater heats said bimetal element causing saidarms to diverge, pin means pivotally mounting said bimetal element atsaid web portion, calibrating means engageable with one of said arms,overcenter means, the other of said arms, upon predetermined deflectionthereof engaging and thereby actuating said overcenter means, andcontact means operable by said overcenter means upon actuation thereof.

2. A multiphase overload protective device including for each of saidphases an electric heater, a generally U- shaped bimetal element havingspaced arms connected by a web portion, said element mounted in spacedrelation with respect to said heater and in close proximity thereto sothat heat generated by current flow through said heater heats saidbimetal element causing said arms to diverge, pin means pivotallymounting said bimetal element at said Web portion, calibrating meansengageable with one of said arms; a common adjusting member, saidcalibrating means of all phases mounted to said common adjusting member;main contact means; a common tripping member connected to said contactmeans for operation thereof; the other arm of each of said elementsbeing connected for operation of said tripping member upon theoccurrence of predetermined heating of any of said bimetal elements.

3. A device as set forth in claim 1 in which the heater extends betweenthe arms of said element.

4. A device as set forth in claim 3 in which the heater is a generallyU-shaped member whose arms are positioned generally parallel to the armsof said element.

5. A device as set forth in claim 2 also including an insulating housinghaving partition means defining an individual main compartment for eachof said phases, each of said main compartments having disclosed thereinan individual one of said heaters and an individual one of said bimetalelements, said main compartments being separated from one another by airspaces so as to reduce heat conduction between phases.

6. A device as set forth in claim 5 also including a manual resettingmeans positioned between a first and a second of said main compartmentsand an automatic resetting means positioned between said second maincompartment and a third of said main compartments.

'7. A device as set forth in claim 6 in which the housing also definesanother compartment wherein said contact means is disposed.

8. A device as set forth in claim 5 in which the housing is constitutedby a rear cover and a hollow base having a generally closed front and anopen back, an adjusting element for selectively positioning saidadjusting mem ber, said adjusting element positioned so as to beaccessible for operation from the front of said base.

9. A device as set forth in claim 5 in which said adjusting member is apivotally mounted rod having an individual radial extension projectinginto each of said main compartments, each of said calibrating meansmounted to an individual one of said extensions.

10. A device as set forth in claim 5 in which for each of said phasesthere also is a spring trip means interposed between said other arm ofsaid bimetal element and said common tripping member.

11. A device as set forth in claim 10 in which each of the spring tripmeans includes a bistable overcenter mechanism.

12. A device as set forth in claim 11 in which said tripping member is apivotally mounted rod having an individual radial projection engageableby an individual one of said spring trip means, said rod also having anadditional projection for operating said contact means.

13. A device as set forth in claim 12 in which said adjusting member isanother pivotally mounted rod, each of said calibrating means mounted toan individual radial extension of said another rod.

14. A device as set forth in claim 13 also including biasing meansurging said another rod to pivot in a first direction and an adjustingelement positioned to limit movement of said another rod in said firstdirection.

15. A device as set forth in claim 14 also including an insulatinghousing having partition means defining an individual main compartmentfor each of said phases, each of said main compartments having disposedtherein an individual one of said heaters and an individual one of saidbimetal elements, said main compartments being separated from oneanother by air spaces so as to reduce heat conduction between phases.

No references cited.

BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITTER, Assistant Examiner.

1. AN OVERLOAD PROTECTIVE DEVICE INCLUDING AN ELECTRIC HEATER, AGENERALLY U-SHAPED BIMETAL ELEMENT HAVING SPACED ARMS CONNECTED BY A WEBPORITON, SAID BIMETAL ELEMENT MOUNTED IN SPACED RELATION WITH RESPECT TOSAID HEATER AND IN CLOSE PROXIMITY THERETO SO THAT HEAT GENERATED BYCURRENT FLOW THROUGH SAID HEATER HEATS SAID BIMETAL ELEMENT CAUSING SAIDARMS TO DIVERGE, PIN MEANS PIVOTALLY MOUNTING SAID BIMETAL ELEMENT ATSAID WEB PORTION, CALIBRATING MEANS ENGAGEABLE WITH ONE OF SAID ARMS,OVERCENTER MEANS, THE OTHER OF SAID ARMS, UPON PREDETERMINED DEFLECTIONTHEREOF ENGAGING AND THEREBY ACTUATING SAID OVERCENTER MEANS, ANDCONTACT MEANS OPERABLE BY SAID OVERCENTER MEANS UPON ACTUATION THEREOF.